The present invention relates generally to filters, and more particularly, to a disposable filter which is adapted to retain contaminant material of a certain particle size, which is adapted to form a part of a filter medium using particles initially retained by the filter, and which is particularly designed so as to absorb little if any of the substance from which the contaminants are filtered.
While capable of other uses, filters according to the present invention are advantageously used to separate and retain impurities from the solvent used in parts washers of the type in which cleaning solvent is continually pumped from a reservoir and directed over parts received in a sink or other retainer, and wherein the solvent thereafter is filtered somewhat and permitted to return to the reservoir to await eventual recirculation.
In one form of parts washer, namely, parts washers of the type described and claimed in U.S. Pat. No. 3,522,814, solvent filtration and cleaning has generally been accomplished by permitting the solvent to flow over a mass of cotton waste held on a perforated, filter-retaining horizontal wall forming a part of the washer unit. This concept has the advantage of fairly effective filtration, economy, and ease of service. However, as solvent has become significantly more costly in recent times, as filter material has become less readily available, and as the convenience of the customer being serviced has become more important, the various types of filtration apparatus and methods used in the prior art may be seen to be capable of further improvement.
Thus, for example, whereas cotton waste material was commonly available in the past for very low prices, and whereas such material was effective because of the natural absorbency of cotton, this situation has changed in two important respects. First, pure cotton waste is no longer readily available, because, whereas cotton was used almost exclusively in the past for many articles of clothing, for toweling and rags, etc., this is no longer the case. Today, almost all articles containing cotton also contain significant portions of synthetic fibers, such as fibers of nylon and fibers of various polyester and acrylic materials. Accordingly, such materials lack consistency and the ability of pure or almost pure cotton to absorb impurities from the solvent.
Secondly, while many parts washers in the past were serviced by removing and throwing away the cotton waste, and removing the solvent for discarding or reclamation, the price of solvent today is so high that reclamation thereof is economically desirable and the waste thereof occasioned by solvent absorption within cotton fibers is economically disadvantageous.
Still further, users of parts washers have become increasingly aware of fire and inhalation hazards caused by leaving solvent-filled filter rags on or about the premises of the parts cleaners users. Accordingly, there has been a need for an improved filter and filtration systems which is especially adapted to meet the needs of parts washers users of today.
Accordingly, an object of the present invention is to provide an improved filter assembly.
A further object is to provide a filter unit of a type having significant particle-retention capability, but little or no absorptive capacity.
A further object is to provide a filter having a plurality of openings of a graduated size, and adapted to permit retention of filtered material by the smaller openings and ready passage of fluid through larger openings.
Another object is to provide a filter which will retain particles of dirt or the like, both by reason of screen opening size and by reason of settling or sedimentary action.
A further object is the provision of a filter adapted to employ, as a part of the filter medium, certain of the particles initially received and retained by the filter itself.
Yet another object is to provide a filter particularly adapted for use in cleaning fluids which are continually recirculated, and which often intermittently present to the filter varying loads of material to be removed by filtration.
Still another object is to provide a filter having a neck portion preformed for ready reception in an open drain or like opening, and also capable of being deformed or folded for ready removal.
A still further object of the invention is to provide a filter of a flexible but non-extensible material, and particularly a filter adapted to present a large interior volume, with filter openings on the exterior thereof only.
Another object is to provide a filter having a series of openings which increase in size as they are more remotely spaced from the bottom of the filter.
The foregoing and other objects are accomplished by providing a filter assembly having a neck portion including a relatively rigid collar defining a filter inlet opening, a flexible, bag-like body portion of enlarged volume, a plurality of holes or openings at varying size, with the openings disposed nearest the bottom of the body, with such body being in the form of a perforated but otherwise impermeable, flexible sheet material, whereby a medium to be filtered and passing repeatedly through the filter body will be cleaned by entrapment of particles retained by the smaller opening and by sedimentation of particles from the liquid retained in said filter body.